The invention generally relates to paint spray booths. More particularly, the invention concerns an air distribution arrangement for use in a spray booth plenum and adapted to improve the uniformity of the output airflow from the plenum into the spray booth paint application zone.
Down draft airflow uniformity is desired in order to maximize paint transfer efficiency which is a function of air velocity differences within the paint application zone. Particularly in powder spray booths, velocity differences cause overspray in high velocity areas and paint buildup on the painted object in lower velocity areas. In addition to inefficient paint transfer, overspray leads to buildup problems on booth walls and application apparatus surrounding the paint spray application area and additional costs relating to recovery and separation of the overspray.
In traditional paint spray booths, bag filters are distributed over the length and width of the plenum in order to distribute air evenly into the plenum's lower compartment. However, this arrangement has not been found to provide the desired uniformity of airflow. Further, the use of bag filters requires an upper plenum compartment containing the bag filters and a lower plenum compartment equipped with a filter media through which the air from the upper compartment must pass to reach the paint application zone.
Additional methods of minimizing overspray buildup in a powder spray booth are discussed in U.S. Pat. No. 5,178,679, assigned to the assignee of this application, and incorporated herein by reference. However, the methods discussed therein relate to air velocity control mechanisms disposed in the paint application zone. Conversely, the invention disclosed herein minimizes the velocity differences of the air exiting the spray booth plenum thereby increasing paint transfer efficiency and decreasing overspray.